The transmission capacity in optical communications has been dramatically increased. In recent years, optical communications having a transmission capacity of 40 Gbps or 100 Gbps have been proposed. For example, in optical communications of 40 Gbps, four optical signals having a rate of 10 Gbps and different wavelengths are multiplexed. In optical communications of 100 Gbps, four optical signals of 25 Gbps or ten optical signals of 10 Gbps are multiplexed.
In order to achieve a transmission capacity of 40 Gbps or 100 Gbps, the transmission capacity of the optical transceiver has been expanded. For example, “CFP MSA CFP4 Hardware Specification, Revision 1.1” (NPL 1) discloses an optical transceiver for supporting a 40 Gbps interface and a 100 Gbps interface for, for example, Ethernet (registered trademark) and telecommunications.
For example, US Patent Application Publication No. 2016/0149643 (PTL 1) discloses an optical transceiver including an integration of four optical devices each having a transmission rate of 10 Gbps. The optical transceiver multiplexes four optical signals having different wavelengths to equivalently obtain transmission rates of 40 Gbps and 100 Gbps. For example, US Patent Application Publication No. 2011/0103797 (PTL 2) discloses an optical transceiver including four separate optical devices.